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Fall-Foundational Sciences Year 1 > Muscle Tissue > Flashcards

Muscle Tissue Flashcards

1
Q

types of muscle

A
  1. skeletal
  2. cardiac
  3. smooth
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2
Q

contraction mediated by

A

thin and thick myofilaments

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3
Q

thin filaments

molecular comp

A

globular actin monomers (G-actin) > polymers> double helix filamentous actin

troponin complex (3 subunits)

tropomyosin molecule

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4
Q

troponin complex

A

TnC - bind calcium
TnT- attach tropomyosin
TnI- inhibit actin/myosin interaction, binds troponin complex to actin molecules

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5
Q

tropomyosin molecule

A

alpha helix of 2 polypeptide chains
each molecule covers 7 G-actin active sites
head to tail assembly of molecules = tropomyosin filament

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6
Q

thick filaments

composition

A

myosin II (200 molecules)

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7
Q

myosin molecule

components

A

2 heavy chains + 4 light chains

heavy chain = alpha helix tail w/ globular heads
light chain = small chunks/golf balls on globular heads

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8
Q

trypsin + myosin molecule

A

trypsin breaks myosin molecule into 2 segments
heavy meromyosin- 4 light chains, 2 globular heads, short twisted tail
light meromyosin- long twisted tail

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9
Q

heavy meromyosin + papain

A

papain further breaks down heavy
two S1 (2 light chains + 1 head)
one S2 (short twisted tail)

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10
Q

thin + thick filaments

A

= sarcomere
contracting unit of skeletal/cardiac muscle
cylindrical shape

thin and thick alternate/overlap

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11
Q

myofibril

A

combo of bands (A/H + I/Z), assembly of sarcomeres

enclosed in skeletal muscle cell (fiber) > fasciculus (bundle)

assembly of sarcromeres

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12
Q

A band

A

thin and thick
bisected by H band (thick only)

dark and wide

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13
Q

I band

A

thin only
bisected by Z (attachment for thin filaments)

light

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14
Q

sarcomere accessory proteins

purpose

A

attach, space, algin myofilaments for even, precise, orderly arrange

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15
Q

alpha actinin

A

attach thin filaments to Z disk

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16
Q

nebulin

A

thin filaments to Z disk
2 molecules / 1 thin

nonelastic

17
Q

titin

A

thick to Z
elastic so produce tension/force generating

4 titin/ 1 thick

18
Q

midline proteins

M line

A

myomesin
C protein
thick to M band (middle of H)

19
Q

endomysium

skeletal muscle

A

surrounds each muscle fiber/cell

retiuclar fibers + external lamina

20
Q

perimysium

skeletal muscle

A

thin collagenous CT
surround each bundle/fascicle

21
Q

epimysium

A

aka deep fascia (dense, irregular collagenous CT)
surrounds gross muscle
nerves and vessels

22
Q

skeletal muscle

appearance

A

banding/striated longitudinal

mulitnuclei pushed to periphery- euchromatic, oval shape

uniform size of cells cross section

in LM only see A (dark) and I (light) bands

23
Q

cardiac muscle

appearance

A

weak striated/banded but branched so different size (cross sections)

have intercalated discs and capillaries, and atrial granules (hormones inside)

24
Q

smooth muscle

appearance

A

spindle shape
1 nucleus in middle
different size cells (cross section)
no striations/sarcomeres

sardines, little extracellular space

25
Q

skeletal muscle

composition

A

T tubules- invaginations of sarcolemma, continuous w/ ECS, carry nerve impulses

SR- elaborate sER meshwork surrounding myofibrils

terminal cisternae- part of sER, next to T tubules, store Ca in lumen

26
Q

triad of skeletal muscle

A

one T-tububle + two terminal cisternae

27
Q

motor unit

A

neuron + all skeletal muscle fibers it innervates

have end plates aka myoneural junction - 1 per/fiber, have axon terminal (Ach) + synaptic cleft + skeletal muscle cell sarcolemma/post synaptic membrane

28
Q

myasthenia gravis

A

acetylcholine (Ach)
antibodies attach to receptors so Ach can’t bind = muscle weakness

29
Q

atrial granules

cardiac muscle

A

have atrial natriuretic peptide and brain natriuretic factor (diuretics, act on kidneys to lower BP or loss of water/sodium)

most numerous in R atrium fibers

30
Q

intercalated discs

A

specialized junctions of cardiac muscle

transverse portion: fascia adherens (transmit contractile forces cell to cell) and desmosomes (bind cells together)

lateral portion: gap junctions, allow ion flow

31
Q

purkinje fibers

A

specialized cardiac muscle
like batteries to ignite regular cells to contract

conducting system

@ endocardium (inner most layer heart)

32
Q

dystrophin

accessorry protein

A

cytoplasmic
binds thin to laminin (external lamina surrounding fiber)

if absent = muscular dystrophy aka weakness and wasting/ atrophy

33
Q

caveolae

smooth muscle

A

pinocytotic vesicles
bubble like on inner surface of cell membrane
release Ca into cell for contraction

34
Q

myofilament bundles

A

criss cross to form dense bodies

points of attachment on internal suface of cell membrane to anchor

35
Q

presynaptic events

A
  1. nerve transmitted down axon
  2. impulse reaches presynaptic membrane
  3. Ca2+ ions enter terminal
  4. synaptic vesicles attach to inner surface of presynaptic membrane
  5. synaptic vesicles release Ach into cleft

start with nerve down axon
end w/ Ach release

36
Q

postsynaptic events

A
  1. Ach binds to receptors on postsynaptic membrane
  2. Na+ ions enter skeletal muscle cell
  3. K+ ions exit skeletal muscle cell
  4. sarcolemma becomes depolarized
  5. depolarization spreads to T-tubule opening

start Ach binding receptors
end at T-tubules

37
Q

events inside skeletal muscle cell

A
  1. depolarization spreads to T-tubule membrane
  2. nerve impulse carried deep into muscle cell
  3. depolarized T-tubule trigger change in permeability of terminal cisternae of SR @ each side of T-tubule
  4. Calsequestrin from SR releases Ca2+ ions into cytoplasm
  5. Ca ions attach to TnC of troponin = conformational change
  6. TnT pushes tropomyosin filaments deeper into groove of actin to uncover active sites
  7. myosin head associates w/ active site of actin monomer using ATP
  8. head and rod of myosin bend to pull actin filament over myosin filament = sliding of thin filament towards midline

Fall-Foundational Sciences Year 1 (33 decks)

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